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On 5 Jan 2005 09:09:24 -0500, (Scott Dorsey) wrote:
Send me an address and I'll send you a cable with a resistor in it. Put
it on your S-PDIF line and your error rate will go through the roof. It
will sound different. snip
As someone with over 20 years in the telecommunications field, the
last half being digital, I'll end this by saying that the ONLY
parameter that directly affects digital is level...period...as long as
the cables are within specified length. Over that length, lump
constants start rounding leading edges, but it STILL doesn't
matter...as long as the threshhold is reached for a 1, -1 or 0, who
cares what the leading edge looks like??
I did an experiment similar to the "coathanger" experiment years ago,
using SO cord as a patch cord on a 110 ohm digital patch trunk at the
DS-1 level. Results, NO change. Of course, with analog, things would
have gotten nasty on a 600 or 135 ohm balanced pair if this went for
any distance, especially at group frequencies (60-108 KHz) or above,
but digital didn't care at the DS-1 and E-1 levels, 1.544 and 2.048
Kb/s respectively. At 45 MB/s (DS-3), then things went to coax and
loss was indeed a factor. The cure? Crank the gain up a little on
the transmit side, and I got error free performance on the
receive...even using SO cord at the DS-3 level. Would I use this as
an in-service thing? Hell no...110 ohm balanced patch cords (same
things as used for 600 ohm voice, actually) and RG-187 coax with WECO
connectors ONLY. But, it proved my point...digital's either "good" or
it's "bad," there are no varying impairments like in analog, just
varying bit error rates.
I swear, I need to go into the snake oil business. There's too much
money to take away from fools who obviously don't need it.
dB
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